A metaphor could be the Nolans/Goyer just wanted to get Bane away from the picture

He wanted to kill Bruce in a cheap manner, so he got a cheap death. That's how I see it. I don't mind the death myself except I'd change it up with these: Catwoman doesn't have a witty line after she kills Bane and the scene just jumps to something else, and during Gordon's speech at the end, while we see Gothamites walking out of their houses, the orphans looking where the nuke detonated, we get a snippet of City Hall where a police officer walks out of the building holding unto Bane's shattered mask.

Read your post again and ask yourself if you're asking a very silly question, lol. Why would Bruce Wayne want to leave Gotham but still be called Bruce Wayne especially when he's dead in the eyes of Gotham?

I know the reason behind them all I just like asking people because they might pick up on something else that I have not.